Circuit breaker with handle seal



April 1, 1958 R. w. DUNHAM CIRCUIT BREAKER WITH HANDLE SEAL Filed Oct. 28, 1955 INVENTOR. J Robert M. Dunham HIS ATTORNEY to the other.

United States Patent M CIRCUIT BREAKER WITH HANDLE SEAL Robert W. Dunham, Plantsville, C0nn., assignor to General Electric Company, a corporation of New York Application October 28, 1955, Serial No. 543,430

1 Claim. (Cl. 200-168) My invention relates to electric circuit breakers and more particularly to circuit breakers which are totally enclosed and include an operating handle projecting through the enclosure for permitting manual operation thereof.

In such manually operable circuit breaker constructions, it is very desirable that some means be provided for preventing the escape of .hot gases or flame from around the opening in the casing through which the manually operable handle extends. While various constructions have been utilized or proposed for this purpose in the past, such constructions sufier from various drawbacks and disadvantages. In general such prior constructions have included a one-piece molded handle having a manually engageable portion projecting through an opening in the circuit breaker casing and an enlarged base portion adapted to mount on a member pivotally supported within the casing and including arcuate flanges or skirts adapted to underlie the opening in all positions of the handle. Because of the necessity of providing clearances for manufacturing tolerances or dimensional variations, such handle cannot be designed to be in intimate contact with the underside of the cover. In addition, the oppositely directed skirt portions must have room within the casing to move as the handle is swung from one extreme position This utilizes valuable space that otherwise might be occupied by mechanism parts.

It is an object of the present invention to provide a manually operable handle construction for electric circuit breakers and switches which functions to seal the handle opening at all times, even in the absence of internal pressure.

It is a'further object of the present invention to provide a manually operable handle construction for circuit breakers and switches which occupies a minimum of space inside the circuit breaker casing, whereby the casing dimensions may be made smaller.

Another object of the invention is to provide a circuit breaker handle construction including such sealing means which is relatively inexpensive and easy to assemble.

Other objects and features of the invention will become apparent to those skilled in the art from the following detailed description and appended drawing illustrating a preferred embodiment of the invention.

In accordance with my invention in one form, I provide a circuit breaker including a pivotally supported manually operable handle member having a manually engageable portion projecting through an opening in the breaker casing, a shouldered portion within the circuit breaker casing and a generally rectangular, thin, flexible insulating shield between the shouldered portion of the handle and the underside of the casing wall and having an aperture through which the manually engageable portion of said handle extends, the said shield being deformed by its engagement between the top wall of said circuit breaker casing and the shouldered portion of said handle, whereby its ends press upwardly against the underside of said top wall of the casing and its central portion presses 2,829,222 Patented Apr. 1, 1958 downwardly against the shouldered portion of said manually operable handle.

My invention will be more fully understood by reference to the following detailed descriptiontaken in conjunction with the accompanying drawing, in which:

Figure l is a side elevation view of an electric circuit breaker incorporating my invention, a portion of the casing thereof being broken away to show the handle construction;

Figure 2 is an exploded view in perspective of the manually operable handle construction utilized in the circuit breaker of Figure 1;

Figure 3 is an exploded side elevation view in section of the manually operable handle and its support of the circuit breaker of Figure 1.

Referring particularly to the drawing, I have shown my invention as embodied in an electric circuit breaker comprising an insulating enclosing casing 10 which is generally rectangular in form and which includes a gen erally planar top wall 11 having an aperture or slot 12 therein through which projects the manually engageable portion 13 of the handle assembly 14.

The manually operable handle assembly14 is pivotally supported in the casing on pins 15 and includes an insulating portion 16 and a metallic supporting portion 17 v on which the insulating portion 16 is mounted by suitable means such as by downwardly extending side portions 18 which straddle the metallic portion 17 and are attached thereto by suitable means such as by screws 19. The interconnection between the insulating portion 16 and the metallic portion 17 is further assisted by the engagement of other portions thereof such as the downwardly bent end portion 22 of the metallic handle support engaging the surface 23 (Figure 3) of the manually operable handle portion and by a depending generally circular boss 24 extending into a corresponding circular opening 25 (Figure 2) in the handle support.

The manually engageable portion 13 of the handle is provided with an enlarged inner portion having a generally arcuate surface 26 which, when the handle is assembled in the breaker 10, is closely spaced from the undersurface 27 of the top wall 11 of the enclosing casing 10. For the purpose of sealing the handle opening 12 by cooperation with the surface 26 of the manually operable handle and with the undersurface 27 of the top wall 11 of the circuit breaker casing, I provide a thin planar insulating shield 28 which is generally rectangular in form and has an aperture 29 therein adapted to fit closely over the manually engageable portion 13 of the handle memher. The shield 28 is preferably constructed of a tough, resilient insulating material such as glass-fiber-reinforced polyester plastic. The insulating shield 28 is preferably fiat in its natural condition and intermediate portions thereof may remain flat during use, as at 28b in Figure 1. In general, however, the shield 28 is constrained to assume a generally arcuate position in use by reason of the portion 26 of the handle assembly 14 pressing upwardly on the central portion thereof, which in turn causes the opposite end portions 28a and 28b to press against the underside 27 of the top wall 11 of the circuit breaker casing. Thus, without the use of auxiliary springs and without depending on the force of internal gas pressure, the insulating shield 28 is always in sealing engagement with the handle 13 and the casing 11.

It will be observed that while the insulating shield 28 is always maintained in a slightly bent condition so as to be biased in sealing engagement in the manner described,

it does not move in an arcuate path concentric with the handle member 13. For instance, end 28a of the shield 28 is in engagement with the undersurface 27 of the top wall 11 at all times, and its position at any time is determined by the shape of this surface. The surface 27 and the surface 27a are preferably curved on a radius substantially greater than the radius of the portion 26 of the handle member 13. By means of this construction, shield 28 does not travel. inwardly toward the center of the enclosure 10 any substantial amount. ,T his, taken together with the fact that the shield 28 is of relatively thin construction, results in a greater proportion of the interior space of the casing 10 being available for the mechanism of the circuit breaker.

It will be seen that I have provided a novel and effective handle construction for enclosed electric circuit breakers which, while extremely effective in providing handle-sealing against the escape of hot gases, also provides an effective dust-seal and results in a more compact structure than would otherwise be possible of such circuit breaker, in addition to being inexpensive and easy to as semble.

While a preferred embodiment of the invention has been specifically disclosed, it will be understood that variations thereof will become readily apparent to those skilled in the art and I intend to cover all such modifications as fall within the scope of the appended claim.

What I claim as new and desire to secure by Letters Patent of the United States is:

An electric circuit breaker comprising an enclosing casing having an aperture, in a wall thereof, a manually operable handle member pivotally supported within said casing 011 a pivotal axis remote from said wall and having a portion projecting through said aperture, an enlarged shouldered portion on said manually operable member within said casing and closely spaced from the inner side of said wall, said enlarged portion being substantially smaller than the size required to close said aperture in all positions of said handle, said wall having its inner surface adjacent said aperture curved on an arc of radius substantially greater than the radius of the arc of movement of said manually operable member, and a thin rcsilient insulating shield carried by said handle member and deformed from its natural condition when in mounted condition whereby its natural resilience maintains its center portion in downward sealing engagement with said enlarged portion of said manually engageable handle memher and its end portions in upward sealing engagement with said arcuate inner surface portion of said Wall.

References Cited in the file of this patent UNITED STATES PATENTS 2,071,848 Lindstrom Feb. 23, 1937 FOREIGN PATENTS 26,899 Great Britain Nov. 19, 1909 

